1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive device and a method of producing the same.
2. Description of the Background Art
As one form of piezoelectric/electrostrictive device, there is known a piezoelectric/electrostrictive device that includes a base having a pair of right and left movable parts and a fixing part that connects the movable parts with each other at one end thereof and a piezoelectric/electrostrictive element is disposed on at least one side of the movable parts of the base. There is also known a piezoelectric/electrostrictive device that includes a base having a pair of right and left movable parts, a fixing part that connects the movable parts with each other at one end thereof, and a mounting part that connects the movable parts with each other at the other end thereof and a piezoelectric/electrostrictive element disposed on at least one side of the movable parts of the base. The above-mentioned piezoelectric/electrostrictive devices are disclosed in the specification of European Patent EP1017116A2.
The piezoelectric/electrostrictive device of such a form has a function of operating the movable parts caused by the displacement operation of the piezoelectric/electrostrictive element or a sensing function of sensing the displacement of the movable parts input from the side that is sensed, with the use of the piezoelectric/electrostrictive element. By effectively using these functions, the piezoelectric/electrostrictive device is used in a wide range of fields, such as those described below.
Piezoelectric/electrostrictive devices of such a form are used as active elements such as various transducers, various actuators, frequency region functional components (filters), transformers, vibrators and resonators for communication or mechanical power, oscillators, and discriminators, various sensor elements such as supersonic wave sensors, acceleration sensors, angular velocity sensors, impact sensors, and mass sensors, and various actuators that are put to use for displacement, positioning adjustment, and angle adjustment mechanism for various precision components of optical instruments and precision apparatuses.
Piezoelectric/electrostrictive devices are formed typically by cutting a device master into a suitable size, and the device master is constructed by bonding a piezoelectric/electrostrictive element onto both of the front and rear surfaces of a base master via an adhesive, or is constructed by integrally forming these. Here, the base master is constructed by laminating and baking plural sheets.
Thus, the piezoelectric/electrostrictive device having such a form has a large number of construction components, so that the device is produced at a high cost and through a cumbersome assembling work. Moreover, since the construction components are bonded via an adhesive, there arises a variation of adhesion between the construction components, giving rise to a fear that the device characteristics may be adversely affected.
Further, the piezoelectric/electrostrictive device having such a form is produced by adopting means to cut a device master suitably into a large number of devices. Therefore, the piezoelectric/electrostrictive devices formed by cutting are contaminated with dusts generated at the time of cutting, cutting liquid, and organic components such as an adhesive or wax used for holding the device master at the time of cutting, so that it is not easy to clean the piezoelectric/electrostrictive device.
Also, in the case where the base is constructed with ceramics, one must adopt a hard ceramic material such as zirconia, since the ceramics are liable to be split. Even if a hard ceramic material is adopted, one must choose a suitable cutting condition to prevent a loss of material through nicks or cracks. Further, since the base is made of a hard ceramic material, the machining process is difficult to be designed and, in order to increase the number of machining products, one must give a careful consideration such as use of a large number of machining apparatuses having different functions.
The base can be constructed with a metal material. The use of a metal material, however, gives rise to an oxidized end surface caused by friction heat during the cutting process and burrs remain on the processed end surface. Consequently, another processing step must be added to remove the burrs. Further, the piezoelectric/electrostrictive element can be tested only after the device master is cut.
Meanwhile, the device cut out from the device master is preferably cleaned by adopting ultrasonic cleaning that can easily remove the contamination. However, if a strong ultrasonic wave is used to obtain a high cleaning effect in ultrasonic cleaning, the device may be damaged, and the piezoelectric/electrostrictive element may be broken or peeled off from the base. For this reason, if the ultrasonic cleaning is adopted, one must select a weak ultrasonic wave that does not give damages to the device. However, if such a cleaning condition is adopted, a long period of time is needed in removing the contamination that has adhered at the time of cutting.
Dust generation from the piezoelectric/electrostrictive device may cause the following problems. For example, in the case where the piezoelectric/electrostrictive device is used in an actuator of a magnetic head in a hard disk drive, if dust is generated in the drive, the dust may cause crash of the floating slider onto the medium, thereby raising a fear of data destruction. Also, for the piezoelectric/electrostrictive device itself, the dust may adhere to the electrode of the piezoelectric/electrostrictive element, thereby giving rise to a fear of short circuit. For this reason, a high level of cleaning is required not only in the hard disk drive but also in the device itself.
Therefore, an object of the present invention is to solve the aforementioned problems of the prior art by allowing the base constituting the piezoelectric/electrostrictive device of that form to have an integral structure using one sheet of flat plate as an original plate.